1. Field of the Invention
The present invention relates to an electro-photographic type image forming apparatus and warm-up method for the same.
2. Description of the Related Art
When power is turned on in an electro-photographic type image forming apparatus, the apparatus first performs a warm-up operation (preparatory rotation of a photosensitive drum, and raising of the temperature of a fuser). The photosensitive drum may be rotated a predetermined number of times (two or three times, for example) in the preparatory rotation, and the fuser is heated until it reaches a predetermined stand-by temperature. Therefore, the preparatory rotation of the drum will end while the fuser is still being heated.
When the fuser reaches its stand-by temperature, application of heat to the fuser is discontinued. The fuser""s heat may then be lost to the surrounding environment. This may cause the fuser temperature to drop below its stand-by temperature. If the start button is then pressed on the image forming apparatus, thereby directing the machine to perform an image recording operation, a certain time is required until the fuser temperature returns to the stand-by temperature. This causes the image recording operation to take long, and a user must wait long.
It is an object of the present invention to provide an image processing apparatus capable of quickly performing a print-out operation even if the printout operation is requested after some time has passed since completion of the warm-up operation.
According to one aspect of the present invention, there is provided an electro-photographic type image processing apparatus that includes a heating unit that heats a fuser, a detection unit that detects the temperature of the fuser, and a control unit that stops performing the warm-up operation when the fuser reaches a warm up completion temperature that is higher than a stand-by temperature. When the fuser has been heated to the warm-up completion temperature, the atmosphere around the fuser has also been heated considerably, and the fuser does not lose its heat to its surrounding environment in a certain period. Since the warm up completion temperature is higher than the stand-by temperature, the fuser""s temperature is still high (or close to the stand-by temperature) after completion of the warm-up operation. The image forming apparatus can therefore print out quickly even if a print start button is pressed some time after completion of the warming-up operation.
The fuser""s warm-up completion temperature may be lower than it""s fusing temperature. If so arranged, the image forming apparatus can print out quickly after the power is switched on.
The control unit may maintain the temperature of the fuser at the stand-by temperature after the fuser""s temperature reaches the warm-up temperature. If so arranged, the image forming apparatus can reduce power consumption when it is in stand-by mode.
The control unit may stop the motor after completion of the warm-up operation. This can reduce wear-and- tear on the photosensitive drum.
The control unit may begin printing out image data without stopping the motor if a print signal (command) is given to the apparatus during the interval between the turning on of power and the fuser""s reaching the warm-up completion temperature. This allows the printing to start quickly after power is switched on.
According to another aspect of the present invention, there is provided an electro-photographic image forming apparatus including an exposure unit for forming an electrostatic latent image on a photosensitive drum, a developer for forming a toner image by applying toner to the electrostatic latent image, a transferer for transferring the toner image onto a recording sheet, a fuser for fusing and fixing the transferred image onto the recording sheet, a heater for heating the fuser, a temperature detector for detecting temperature of the fuser, and a controller for adjusting the heater based on the detected temperature such that a warm-up operation is terminated when the fuser reaches a warm-up completion temperature that is higher than a stand-by temperature. Since the warm up completion temperature is higher than the stand-by temperature, the image forming apparatus can start a printing operation immediately or in a very short period anytime after the warm-up operation has been completed.
The warm-up completion temperature may be set to a temperature lower than the fusing temperature. This enables the image forming apparatus to rapidly perform a printing operation anytime after power has been turned on.
The controller may maintain the fuser at the stand-by temperature after completion of the warm-up operation. The image forming apparatus can reduce power consumption while the apparatus is in a stand-by mode.
The heating unit or heater is referred to as a heat lamp 101a in the detailed description, the temperature detection unit or detector is referred to as a temperature sensor 110, and the control unit or controller is referred to as MPU 11, ROM 12, and RAM 13.